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TRACK STRUCTURE on BRIDGES

TRACK STRUCTURE on BRIDGES. Rail and rail joints. Longitudinal profile of rails. Rail cant. Rail joints over the bridge- Small bridges having opening < 6.1 m rail joint should be avoided. For other spans, the preferred position is at 1/3 the span from the ends.

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TRACK STRUCTURE on BRIDGES

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  1. TRACK STRUCTURE on BRIDGES

  2. Rail and rail joints • Longitudinal profile of rails. • Rail cant. • Rail joints over the bridge- • Small bridges having opening < 6.1 m rail joint should be avoided. • For other spans, the preferred position is at 1/3 the span from the ends. • Rail joint should be avoided within 3 m from abutment.

  3. SWR on bridges • SWR may be continued over girder bridges with un-ballasted decks up to 13.3 m opening if symmetrical. • In case of asymmetrical up to 6.1 m opening. • If SWR is laid, no fish plated joint should be located on the girder or within 6 m from abutment • 26 m long rolled rails may also be provided.

  4. Precautions for arresting creep. • Track laid with standard single rails and fish plated joints be isolated with SWR if laid on approaches by providing two well anchored standard rail lengths. • Track laid with standard single rails and fish plated joints be isolated with LWR if laid on approaches by providing 36 m well anchored SWR on either side.

  5. Provision of guard rails • Should be provided on all girder bridges. • Should be provided on Prestressed concrete girder bridges without deck slab. • Should be provided on all major and important ballasted bridges and also on such minor bridges where derailment may cause serious damages. • On all flat top, arch and Prestressed concrete girder bridges with deck slab where guard rail is not provided the whole width of the bridge between parapet walls shall be filled with ballast up to sleeper level.

  6. Design of guard rail

  7. Splaying of guard rail • In the case of through girder bridges on double lines, guard rails should be splayed on either ends. • Other than through bridges splaying be done only on the facing direction. • However the non splayed end should be bent downwards after it is stopped at the end of the abutment and wooden block provided.

  8. Trolley refuse • Bridges with span < 100 m at 100 m. • Bridges with span > 100 m on each pier.

  9. Hook Bolt • Hook bolts tie the sleeper with girder flange. • The lips of the hook bolts will be as per the design of the girder. • Hook bolts are of 22 mm dia with square shank.

  10. Inspection and maintenance of track on approaches. • On bridge approaches, sleepers with arrangement for fixing guard rail should be provided. • Full complement of track fittings on approaches up to 100 m. • Rail level should be maintained and dip immediately after abutment should be avoided.

  11. Continued.. • Rail joint should be avoided within 3 m from abutment. • Joggle plating of AT welds if length of water way is ≥ 100 m and on approaches upto 100m.

  12. Continued.. For important and major bridges: • In case of CST-9 or wooden on approaches, PRC / ST with ERC should be provided up to 100 m / up to full breathing length where ever LWR is provided on approach of bridge. • 90 cm cess width should be provided up to 100 m on approaches.

  13. Inspection and maintenance of track on bridges. • It should be ascertained whether it is central on the rail bearers and the main girders and in good line and level. • The condition of sleepers, spacing and squareness should be checked.

  14. Continued.. • Rail fastenings should be tight. • Condition of path way. • Sand bins should always be filled with dry and loose sand.

  15. Steel sleepers on bridges • It refers to both channel sleeper and H-Beam sleeper.

  16. Introduction Track structure on bridges are different from that on embankment, such as : Ballasted deck bridge – Rails, fittings and sleeper are similar to the track structure on approach except guard rails are provided to prevent over turning of derailed rolling stock. These type of deck is used over masonry arch bridge, RCC/PSC I girder/slab and box, composite girder, PSC I girder/PSC box girder. On steel girder ballasted deck was used by providing steel troughs which were posing problem for repairs / maintenance to corrosion effected members

  17. Steel trough ballasted deck bridge Open deck bridge

  18. Open deck bridge – Space between two sleepers is open hence called open deck. • To support rails on steel girders following type of sleepers are being used : • Wooden sleepers – • are lighter in weight, • easy for handling on bridges, • easy in machining for placements, • minimum simple fittings to hold the rails as well as in maintenance repairs. • Rail free fastening such as rail screw / dog spikes and canted bearing plates over wooden sleepers provided for independent movement of rail. • Due to scarcity of wood and restriction to use wooden sleeper on Indian Railways these are not being used now a days.

  19. Steel channel sleepers – • Introduced as substitute to bridge timbers during 1992 having drawing No. RDSO / B-1636 and B-1636/1. • Subsequently to minimize number of fittings and ease in fabrication and maintenance, revised drawings were issued by RDSO, drawing No. B-1636/R2 and B-1636/1/R2 of channel size 150x75mm. • To avoid thicker packing plates over top flange plate of plate girders of 12.2m, 18.3m and 24.4m spans additional drawing No. B-1636/2 are also issued with increased height of channel size 175x75mm.

  20. STEEL CHANNEL SLEEPERS – • Two types of steel channel sleepers are used: • ISMC150x 230 mm size of cross section, fabricated by rolled channelISMC150x75mm(Drg No.B-1636/R2&B-1636/1-R2) • ISMC 175 x 230 mm size of cross-section, fabricated by rolled channel ISMC-175 x 75 mm (Drg No. B-1636 / 2) .

  21. Length – • Length of steel channel sleeper depends on the type of steel girder bridges and its span

  22. Details of steel channel sleeper – • Sleeper is made by 2 ISMC 150 x 75mm or 175 x 75mm, which are kept back-to-back 80mm apart to make width of 230 mm. Both channels are connected in web by 'T' & plate type diaphragms with fillet weld. • 'T' shape diaphragms are connected below 'T’ head bolt connecting rail clips. In case of loosening of nut, bolt will rest on 'T' diaphragm, so that clip will be in position as well as prevent falling down of bolt. Note: • The top flange plate of welded girder has different width at both ends and at middle portion of girder. Therefore, Length of sleepers on A and B location are different.

  23. Canted bearing plates for rail seat are connected to top flange of both channels with rivets. • Stiffener plates are provided below the rail seat with fillet weld in web between top and bottom flange of both channels as well as in the middle of sleepers. • Track fittings for steel channel sleepers – • Rail fastening arrangement for sleeper is as per Drg No. RDSO/T-5155 to 5164 for BG (60 Kg running rail and 52 Kg guard rail) and as per Drg No. RDSO/T-5197 to 5200 (for 52 Kg running rail and 52 Kg/ 90R guard rail). • Fastening arrangements comprise of a) Bolt- ‘T’ head bolts with spring washers and nuts are used to clamp the clip to canted bearing plate to hold rails. ‘T’ head will facilitate insertion of bolt from top and vice versa removal of the same.

  24. Clip Rubber pads ‘T’ Bolt b) Clips - Either side of rail, clips are provided and tightened with ‘T’ head bolts to keep the rail in Position i.e. Clip prevent lateral movement and uplift of rail but it will allow rail to move longitudinally to facilitate free movement of rail and girder as rail free fasteners. Guard rails are also anchored with both sides (crosswise) by bolt and clip to sleeper top flange. c) Rail Pads - Grooved rubber pads are placed bellow the rail on canted bearing plates. A 10 mm GRSP of suitable size is to be provided between rail and sleeper. To provide smooth surface between rail and pad 2 mm stainless steel plate is embedded in rubber pad.

  25. Clip fittings

  26. Fittings for Guard rail

  27. Rubber pads and pad plate

  28. Nylon chord reinforced elastomeric pad Holes to be made as per rivets at site and sealed with red lead or other paint

  29. Hook Bolt arrangement: Pad Plates

  30. Hook Bolt arrangement: 25 mm rubber pad

  31. Arrangement if there are no rivets

  32. Specification of steel for sleepers – • Steel channel sleeper is critically loaded dynamic structure which directly supports rails of track on girders hence following steel shall be used: a) Bridges located where service temperature does not fall below 0C, steel used shall confirm to IS- 2062 grade 'B0' fully killed. Note: Till such time rolled channel not available of steel to IS - 2062 grade "B0" steel confirming to IS-2062 'A' fully killed can be used. b) Bridges located in below sub zero temperature areas, steel shall be confirming to IS-2062 grade "C" fully killed. • Note: Steel used for fabrication should be tested one and must have mill test certificate clearly indicating the specification and fully killed. Fabricator should maintain the record of steel used with cast mark for verification if required at later date. Rolled section should be within the rolling tolerances and surface defects prescribed in IS-1852.

  33. Precautions - a) Steel sections used in fabrication must have mill test certificate clearly indicating the steel specification conforming to IS-2062 grade “B0‘ or 'C', fully killed. b) Steel plates and rolled sections should be straight and free from twist before cutting for fabrication. c) Oxy-acetylene gas cutting by mechanically controlled torch shall be used and cut edges to be ground. Profile of plate stiffener shall match with the profile of inner web and flange plate of both ISMC or ISHB for snug fit to avoid cracking of weld or root of ISMC or ISHB below rail seat. d) Welding position shall be flat position (down hand welding) either by MMAW or CO2 welding process as well as welding is carried out only by the qualified welders. e) Electrodes shall confirm to IRS-M-28 of class A- 2 or C-1 and wire for CO2 welding shall confirm to specification of class-1 of IRS-M-46-2001. Preferably CO2 welding shall be used for fabrication.

  34. f) Welding procedures requires approval & testing as per Clause-19 of Welded Bridge Code & record of fabrication and test qualification shall be maintained in pro-forma as stipulated in Appendix-V of IRS serial B-1. g) Before welding, all mill scale and dust adjoining weld face shall be removed and surface shall be cleaned and to avoid cracking of weld during service. h) Bearing plates and supporting rails are connected to sleeper by rivet hence drilling of holes in sleeper after manufacture and in bearing plate shall be by drilling jig to ensure accuracy in rail gauge and alignment of rails on bridge. Rivets shall be driven with proper heating for the full length of shank to minimize loosening of rivets during service and reduce maintenance cost. i) Fabrication of H-Beam Steel Sleepers which are suitable for welded plate girders / stringers shall be done as per RDSO Specification BS: 45. Hot dip Galvanization to be done to the fabricated sleeper as per IS: 4759 to prevent corrosion. CBE may permit use of steel H-beam sleeper with painting as per Para 218 of IRBM on economic and other practical grounds.

  35. j) Entire surface of sleeper shall be grit blast cleaned before hot dip galvanizing as per IS-2629. k) Zinc coating weight / thickness is most important factor from corrosion prevention point of view since sleeper is in vulnerable location and affected by disposal of passenger carriage and dropping chemicals and salts from goods wagon. Hence nominal coating weight 610 g/m2 (85-86 μ tk) for long life of 15 to 20 years and 750 g/m2 (105 μ tk) for severe corrosion location of bridge has to be ensured. Inspection - To ensure minimum maintenance & safety of public, fabrication shall be in Civil Engineering Workshop of Zonal Railways or from trades who produce satisfactory evidence of his ability as stipulated in Clause-21 of Welded Bridge Code 2001. Inspection shall be in accordance with Clause No.28, 29, 30, 31, 32 and 33 of Welded Bridge Code of 2001 so that cost of maintenance and repairs will be minimized.

  36. Design dimensions and sections • For girder, location of steel sleeper should be marked and numbered. • Fabrication of steel sleeper should be location specific considering girder center, top flange cover plates, rivet pitch etc. • In case of bridge on curves, location of sleeper should be marked after taking into account the realigned curve. • In case of transition curves the thickness of pad plates should take care of the cant gradient.

  37. Laying of steel sleeper. • Creep should be adjusted and rails pulled back to position ensuring that no joint is supported. • SSP (sleeper seat painting) and the entire top. • Wherever required cross levels and alignment be corrected in advance. • Pad plate below sleeper ? • Pad plates are not required if Neoprene pad is provided to cover the rivet heads. • Can packing plate be used if required to adjust parameters?

  38. ELASTOMERIC PAD - Elastomeric pad between bottom of steel channel sleeper and flange of girder, is essential to prevent cross bending of flange plate causing initiation of cracks in fillet weld or root of rolled angle under load. Sleepers are made up of steel, which is elastic material and cause cross bending under each axle passing. Elastomeric pad should be provided in case of stringer too and thickness of pad should be 25 mm or as stipulated in drawing. FIXING STEEL CHANNEL SLEEPER ON STEEL GIRDERS - Arrangement of fixing of sleeper depends on type of girder, e.g. Plate Girder (Riveted/ Welded), Open Web through Steel Girder. In welded plate girder same thickness of top flange plate is provided through out the length of girder but flange width is different at mid span than the end portions. Steel plate girders of different span (either welded or riveted construction) are not provided with camber. Therefore a rail level on plate girder as well as on entire bridge has to be in one level. Open web girders are pre-stressed & fabricated with camber, so rail level on each span will coincide to camber profile of span.

  39. Splice plates are used for joining the flange plate and stringers irrespective of riveted / welded connection. To maintain uniform level of track for plate girders and cambered level for OWG, the thickness of steel packing plate at different locations are calculated. Different thickness of packing plates and different size of sleepers are worked out for the span and fabricated. Fixing steel sleepers to riveted / welded plate girders / stringers - a) additional M. S. plates at splice joints are provided at top and bottom flanges of the girders and connected to each other by rivets. As per Bridge Code plate girders of standard spans do not have any camber, so rail level on plate girders and on entire bridge has to be in one level. b) For riveted / welded plate girder, suitable thickness of M.S. packing plate to be welded to the bottom flange of individual H-Beam sleeper to maintain the rail level due to thickness of splice plate and second plate (if provided).

  40. c) Surface of M.S. Plate to which the Elastomeric pad is to be bonded shall be cleaned to make it free from dirt, oil, grease, rust, mill scale or any other extraneous matter. Holes of suitable dia. are punched by pressure in elastomeric pad for accommodation of rivet heads at splices & top lateral bracing connection with top flange of plate girder as per site condition. d) To accommodate rivet heads at top flange, holes of 35mm dia. for 20mm dia. rivet are punched by pressure in the elastomeric pad whereas for 22 dia. rivet it should be 38mm dia. hole. So that sleeper does not rest on rivet head and to avoid rocking of sleeper under running of trains. These holes shall be filled with ready mix Zinc Crome priming paint conforming to IS: 2014 after placing the elastomeric pad in position to avoid accumulation of water.

  41. e) Adhesive shall be applied in thin layer uniformly spread both on the surface of the elastomeric pad and M.S. plate to be bonded. After application of adhesive 10 to 15 minutes shall be allowed before joining the two surfaces so as to allow the solvent to evaporate. f) Surface of elastomeric pad to be bonded shall be cleaned by gently rubbing by fine emery cloth for purpose of removing any superficial layers of extraneous matter such as wax. Care shall be exercised during rubbing that the surface of elastomeric pad is not damaged. g) Elastomeric pad shall be joined to the top of the girder using Polychloroprene based self curing adhesive as provided in the RDSO drawings. h) Elastomeric Pad shall be of size 300mm x 25mm x 305mm. IRS Specificationfor25mm thick Nylon Cord Reinforced elastomeric Pad RDSO / M & C / RP-197 / 03. i) Place the rail and fix it by rail fastening assembly as mentioned by Track Directorate of RDSO through a separate drawing.

  42. Fixing of steel sleepers to open web girder – As per steel bridge code all open web steel girder spans are to be fabricated with camber and pre-stressed. So, suitable thickness of steel packing plate with elastomeric pads to accommodate rivet heads is required so as to maintain rail profile which will be similar to camber profile of span to ensure rail in level under passage of train. Precautions to be taken for while fixing of steel sleepers - a) Clean the top flange plate with wire brush and mark the sleeper position. b) Steel channel sleepers can be for any type of girders, however, suitable section shall be chosen depending upon requirement. The arrangement of fixing H-Beam with top flange of girder is suitable only when there are no rivets on top flange. Surface preparation and sleeper seat painting should be done while providing H-beam sleeper on top flange. c) Top flange portion and splice plate (if exists) , additional flange plates and rivet heads of top lateral bracing system is there, steel sleepers to be laid with elastomeric pad & steel packing as mentioned above to accommodate rivet heads and ensure all are in one level.

  43. d) Centre of sleeper should coincide with centre of span to ensure gauge face of alignment of rail. e) After ensuring all sleepers are in level & concentric to the span, sleepers to be anchored with Hook bolt to girder on either side & nuts are tightened and level of sleepers is checked to ensure it is in desired level. f) Steel channel sleepers are available in different height i.e. of 150 mm & 175 mm height, H-Beam sleepers of 200 mm height. So depending upon the requirement suitable steel sleepers along with steel packing plate may be adopted. Mixing of different type of sleepers and different type of track fitting to be avoided. g) Level of the track shall be raised by 50 mm when H-Beam sleeper are provided as compared to the normal 150 mm high steel sleeper. The effect of such rise of track levels on Schedule of Dimension and existing Vertical Clearance on Electrified section shall be taken into consideration before actual laying for such sleepers.

  44. Details of H-Beam steel sleeper for Welded Girder Bridges- BG (Drg. RDSO / B-1636 / 8) H-Beam is designed using standard ISHB – 200 @ 37.3 Kg/m as per standard steel. 20 Ø HSFG bolt is used to connect sleeper to stinger and tightened with torque wrench to develop a force of 147 kN. Plain washer in bolt assembly as per specification IS: 6649 – 1985 Nut of bolt assembly as per specification IS: 6623 – 1985 Bolt as per specification IS: 3757 – 1985 of Property class 8.8 & length depending upon the thickness of filler plate component.

  45. Silent feature Design is suitable for axle load upto 32.5 t and curvature upto 1° This Drg. is suitable for welded plate girders / stringers where there is no splice joints. Arrangement shown in Drg. for fixing H-Beam is suitable when there is no rivet on top flange of girder. Length of sleeper varies for DFC, BG, 25 t loading as shown in this Drg. For rail seat assembly and position of holes refer separate drawing to be issued by Track Directorate of RDSO. Maxm spacing between sleepers shall be 650 mm centre to centre.

  46. Silent feature At rail joints, clear spacing between two consecutive sleepers shall not be more than 200 mm. Surface preparation and sleeper seat painting to be done while providing H-Beam sleeper. Fish plated joint in guard rails to be provided on each pier to facilitate movement of girder ends. Welded guard rails should not be provided. If CE of ZonelRly. considers that guard rail is stiffer enough to prevent bunching of sleepers in the event of derailment, he may decide to dispense of the angles on sleepers.

  47. H-Beam steel sleeper – Seating arrangement for Riveted / Welded plate girders / Stringers & fixing Gangway arrangement for (Drg. RDSO / B-1636/5) IRS specification for 25 mm thick Nylon cord reinforced elastomeric pad RDSO / M&C/RP-197/03 Elastomeric pad is joined to top of girder by Polychloroprene based self – curing adhesive as Dunlop S-759 of M/s Dunlop India Ltd. or PLIBOND of M/s Good Year India Ltd. Dentrite PC-65 of M/s Chandras Chemical Enterprises Pvt. Ltd. or Fevicol SB-97 of M/s Nabula Chemical Pvt. Ltd. or similar type. The solid contents of the adhesive shall be 20 to 22 % and shelf life min One year. Surface of elastromeric pad to be bonded is cleaned by gently rubbing with fine emery cloth for the purpose of removing any superficial layers of extraneous matter such as wax. Care shall be taken during rubbing that the surface of the elastomeric pad is not damaged.

  48. Thin layer of adhesive be applied uniformly both on the surface of the elastomeric pad and MS Plate to be bonded. After 10 to 15 minutes the two surfaces are joined so that solvent is evaporated Elastomeric pad is placed on the top flange of girder to get the impression of rivets head to find out their exact location. For shop rivet (of 20mm ) 35 mm  hole shall be punched in the elastomeric pad where as for field rivets (of 22mm ) 38 mm  hole. Holes are filled by ready mix red lead paint (IS:102) after placing the elastomeric pad in position to avoid accumulation of water. Elastomeric pad shall be joined in position with the MS Plate and whenever practicable roller pressure shall be applied from one end so as to avoid air entrapment / gaps. To accommodate rivet heads holes are punched by pressure in elastomeric pad at connection of splices and top lateral bracing with top flange of plate girder as per requirement.

  49. Surface of MS plate to which the elastomeric pad is to be bonded shall be cleaned to make it free from dirt, grease, oil, rust, mill-scale or any other extraneous matter. For riveted / welded plate girder suitable thickness of MS packing plate to be welded at bottom flange of individual H-Beam sleeper to maintain the rail level due to thickness of splice plate & second plate if provided. Elastomeric pad 25 mm thick should also be provided in case of the stringer. Size and shape of Hook bolt shall be as shown in the Drg. Position of Hook bolt will vary from span to span. 30 mm  hole for 28 mm  Hook bolt in top plate will have to be drilled at site to suit the span. Size of Split pin of Hook bolt is of 4mm  as per IS: 549 Single coil spring washer of Hook bolt as per IS: 3063 14 mm  hole is provided in H-beam top flange to fix Gangway plate by bolt with a taper washer, nut & split pin.

  50. H - BEAM STEEL SLEEPERS • ISHB – 200 is used as H-Beam, suitable for Welded Plate Girders / Stringers of standard spans. Cross section of sleeper is 200 mm x 200 mm, Size and Length as per Drawing No. RDSO / B-1636 / 8. • For riveted plate girders same type of H-Beam with same fixing arrangement is used. Length of H - Beam sleeper varies as per the type of girder bridges. Drg. No. RDSO/ B-1636/ 5.

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